The cultivatable spirochetes will serve as a model for studying spirochetal physiology, chemical and antigenic composition, ultrastructure, and for devising methods for selectively isolating cell structural components. Techniques and information derived from this study will be applied to the pathogenic Treponema and Borrelia. In vitro cultivation and in vivo propagation of Treponema Pallidum and Borrelia hispanica will be investigated. A major goal of this research is the development of a vaccine for syphilis. BIBLIOGRAPHIC REFERENCES: Graves, S.R., Wachter, M.S. and R.C. Johnson. Failure to infect gnotobiotic, colostrum-deprived and normal piglets with Treponema pallidum (Nichols). Brit. J. Venereal Dis. (1975), in press. Livermore, B.P. and R.C. Johnson. The lipids of four unusual non-pathogenic host-associated spirochetes. Can. J. Microbiol. (1975), in press.